Benign prostatic hyperplasia

The traditional goals of treating benign prostatic hyperplasia—symptomatic relief and improved urinary flow rate—have been challenged by a recent study.¹ This study, by McConnell et al, suggests that medical treatment with the 5α reductase inhibitor finasteride can prevent the longer term complications associated with benign prostatic hyperplasia such as acute urinary retention and the need for surgical intervention. This is one of several studies published recently that help us understand more about the risk factors and management of acute urinary retention.

Jacobsen et al reported on the risk factors associated with acute urinary retention in a community study of 2115 men.² They found a direct relation between the risk of developing retention and lower urinary tract symptoms, depressed peak urinary flow rate, enlarged prostate, and old age. This evidence suggests a progressive nature to the disease, which in the past has been lacking and which should be addressed if new goals of management are to be defined. More recently Pickard et al reviewed the surgical outcome in 3966 men undergoing prostatectomy, of whom 1242 presented with acute retention.³ They found that men with acute retention were at higher risk of developing complications and of dying than men who underwent elective prostatectomy. These differences were only partly accounted for by renal impairment, age, and comorbidity.

Given that we can now identify the risk factors leading to acute retention, and that this condition leads to an increased incidence of postoperative complications, the outcomes from the study of McConnell et al raise the question whether all men with benign prostatic hyperplasia should be treated with finasteride to prevent long term complications.

McConnell et al’s study in 3040 men with moderate to severe symptoms and an enlarged prostate compared finasteride with placebo for four years in a randomised double blind trial.¹ Symptomatic relief and improved flow rates were significantly better in the finasteride group, as expected. However, acute urinary retention developed in 99 men (7%) in the placebo group compared with 42 (3%) in the finasteride group (reduction in risk 57%). Similarly 152 men in the placebo group (10%) and 69 in the finasteride group (5%) underwent surgery for benign prostatic hyperplasia (reduction in risk 55%). The differences between the arms of the study were significant 4 months into the study. In terms of numbers needed to treat, this study shows that 15 men would need to be treated for 4 years to prevent one event (surgery or acute retention). These benefits, however, are additional to the impact on symptoms and flow rates in these men in both the short and the long term.

We have good evidence that medical treatment for benign prostatic hyperplasia can be effective, and the meta-analysis by Boyle et al shows that men with enlarged prostates are most likely to benefit from finasteride in terms of improvements in symptoms and flow rates.⁴ This is consistent with its mode of action, which is based on reducing prostate volume. Since Jacobsen et al’s epidemiological study confirmed that men with enlarged prostates were at greater risk of developing acute urinary retention, it would seem logical therefore that the most cost effective way of achieving the additional benefits identified in McConnell’s study is to use finasteride mainly in men with enlarged prostates.

This leads us to define a practical approach to use finasteride selectively in the right patients. It is unrealistic to suggest that all men with lower urinary tract symptoms undergo transrectal ultrasound to assess the size of the prostate. A simpler approach is to estimate prostate size from a digital rectal examination (which should be carried out in these men anyway to help exclude the presence of prostate cancer). A study comparing the use of digital rectal examination and ultrasound to assess prostate size concluded that doctors performing digital rectal examinations tended to underestimate the size of the prostate. Thus a pragmatic interpretation of the digital examination should be: “If it feels big, it is big.” This straightforward technique would facilitate implementing these recent findings into practice in both primary and secondary care.

Now for the first time in benign prostatic hyperplasia we have evidence that appropriate medical intervention can be used to provide a complete management strategy. Unlike other therapeutic areas such as hypertension or hyperlipidaemia, where such interventions may be used solely to achieve a long term goal, we have the opportunity both to provide symptomatic relief, the principal short term goal, and to reduce long term complications.